Abstract Over the last forty years, mothers have entered the workforce in record numbers. Especially for poor, working-class, and/or minority families, economic challenges have created a strong need for mothers to work outside of the home. In rural areas marked by high poverty, families have limited access to employment that provides standard working hours, high pay, and benefits. Instead, family members are employed in shift, part-time, or seasonal work, and often work several jobs to meet the needs of their family. The geographic isolation associated with rurality has led to increased stress for families, who drive long distances to jobs, health care, child care, and schools, while juggling work and family schedules and unreliable transportation. These challenges have left many families, but especially poor and rural families, struggling to gain access to child care settings providing high-quality, timely, and affordable care for their young children. These constraints are likely associated with child care instability, which is defined as sequential changes in child care settings over time. Despite high incidence rates of child care instability and evidence suggesting that child care instability is negative for children, no studies to date have used rigorous statistical models to account for family selection into child care or followed children through third grade to determine if potential negative influences of instability are long-lasting. Furthermore, no studies have sought to understand the mechanisms by which instability may influence children's longitudinal outcomes, such as child attachment behaviors and learning behaviors. These research gaps are especially apparent for families living in high-poverty rural areas. Data for this project will be drawn from an epidemiological study that oversampled for poor and African American families (N = 1,292), providing an unprecedented opportunity to examine these associations in a large, diverse, and at-risk population.